Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
int h,w;
char c[52][52];
int cc[52][52];
void dfs(int i,int j){
  if(i!=h||j!=w){
    if(c[i+1][j]=='.'&&cc[i][j]+1<cc[i+1][j]){
      cc[i+1][j]=cc[i][j]+1;
      dfs(i+1,j);
    }
    if(c[i-1][j]=='.'&&cc[i][j]+1<cc[i-1][j]){
      cc[i-1][j]=cc[i][j]+1;
      dfs(i-1,j);
    }
    if(c[i][j+1]=='.'&&cc[i][j]+1<cc[i][j+1]){
      cc[i][j+1]=cc[i][j]+1;
      dfs(i,j+1);
    }
    if(c[i][j-1]=='.'&&cc[i][j]+1<cc[i][j-1]){
      cc[i][j-1]=cc[i][j]+1;
      dfs(i,j-1);
    }
  }
}
int main(){
  int m=0;
  cin>>h>>w;
  for(int i=1;i<=h;i++){
    for(int j=1;j<=w;j++){
      cin>>c[i][j];
      if(c[i][j]=='#')
        m++;
      cc[i][j]=10000;
    }
  }
  cc[1][1]=1;
  dfs(1,1);
  if(cc[h][w]==10000){
    cout<<-1;
    return 0;
  }
  cout<<h*w-m-cc[h][w];
}